Fig. 5.
In vivo growth kinetics of rTGEV viruses. Two- to three-day-old non-colostrum-deprived swine were used to study the growth kinetics of rTGEV viruses containing one (A and D) or more (B and E) endonuclease restriction sites, or partial deletion of gene 7 (C and F). Groups of 12 to 20 piglets were oronasally (2 × 108 PFU/pig) and intragastrically (3 × 108 PFU/pig) inoculated. Virus titers at the indicated number of days postinoculation were determined in the indicated tissue extracts. The whole organs were homogenized to obtain representative samples. Error bars represent standard deviations of the mean from four experiments. (G) Number of surviving piglets at different days postinoculation. Results from a representative experiment of two that gave similar results are shown. Recombinant virus titers were compared with that of the wild-type virus by the Kruskal–Wallis test and, in general, were significant (P < 0.05) between viruses with gene 7 deleted and the wild-type virus.